Golf club body fabricated with long carbon fiber material

ABSTRACT

The present invention comprises a golf club head comprising a face component comprising a striking plate portion and a return portion extending rearward from the striking plate portion. The golf club head further comprises an aft-body attached to the return portion, wherein the aft-body is composed of an injection molded compound comprising long fibers.

CROSS REFERENCES TO RELATED APPLICATIONS

The Present Application claims priority to U.S. Provisional Patent Application No. 61/246,860, filed on Sep. 29, 2009.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a multiple material golf club head. More specifically, the present invention relates to a multiple material golf club head with a compression-molded, thin-walled aft body.

2. Description of the Related Art

The prior art discloses multiple material golf club heads.

There are various problems with the current process for manufacturing multiple material golf club heads.

One problem is the standard compression molding process. The hard metal tooling on both sides of the part makes undercuts impossible without significant increases in tool complexity.

Another problem is the molding compounds are not designed to be used in parts with very thin walls. When wall thicknesses are below approximately 0.080 inch, most standard molding compounds are difficult to mold.

Another problem is that standard molding compounds are not as strong, stiff, or tough as laminated composites made with similar matrix and fiber types.

Another problem is the raw materials for the current laminates are quite expensive. The cost is compounded by the very high scrap rate.

Another problem is that using prepreg requires hand placement of each layer of material into a mold which is a time-consuming and labor-intensive process.

Another problem is that with current latex bladders we are able to avoid undercut constraints, but we lose definition on the inside of our parts. The metal tooling dictates OML of the parts quite well, but the part thickness and IML are determined by the number of plies placed in each area and the amount of pressure exerted on the area by the bladder during the cure. As a result, it is difficult to predict the mass properties of the Fusion body before a part is made. One-piece bladder molded driver bodies do not work well with a body-over-face joint. The lack of precision on the inside of the head makes it difficult to control the geometry of the body where it would meet up with the face. Bladder molded multiple material driver design had been restricted to body-under-face joints so that the body bond surface is a well controlled OML surface. Typical epoxy-based prepregs are designed to cure in 20-30 minutes. In the current multiple material golf club head fabrication process, the latex bladders used to apply pressure during the cure cycle can only be used 2 or 3 times before they need to be discarded. Bladders are a significant cost in the current multiple material driver manufacturing process.

Prior attempts to fabricate portions of a golf club head using polymer materials have been limited in scope and success. Some approaches, such as the CALLAWAY® FT-3® FUSION® construction rely on a laminated composite material consisting of a thermoset polymer with continuous graphite fiber. This material offers extremely good mechanical properties, particularly toughness, strength, stiffness and light weight but it's expensive and processing is very labor intensive (multiple plies of material are hand laid into a mold). Because of the hand labor involved in this process it is limited in production rates achievable per tool and cycle times are on the order of 10 minutes per part.

Other manufacturers of golf club heads have used unreinforced thermoset and thermoplastic polymer materials to fabricate a head. This construction is inexpensive and can be produced with very short cycle times (<1 minute). However, this construction is inefficient because of the relatively low strength of unreinforced polymers. These designs require very thick walls, or may in fact have to be completely solid in order to achieve adequate durability. Some unreinforced polymers such as polycarbonate are extremely tough and may be sufficiently durable, but are too flexible to meet the USGA requirement for rigidity. Bodies made of unreinforced thermoset are not competitive for this application.

Other designs use short fiber reinforced polymers. Short fiber reinforcement is commonly used for injection molding of thermoplastic polymers. Short fibers (graphite or fiberglass) are typically about 0.040 inch long when introduced into the molding process. The in-situ lengths are generally even shorter than this due to fiber breakage during processing. Short fiber reinforced polymers can have fairly good strength, but generally poor toughness. Heads made from these materials need to have thicker walls to withstand the stresses resulting from the club head to ball impact. Further, these materials tend to be more sensitive to geometric discontinuities such ad styling features that may be desired on the surface of a club head. Such discontinuities require additional thickness to accommodate local peak stresses. Otherwise, the low toughness of these materials can allow rapid propagation of even a small crack in a local area that's over stressed. Increased thickness results in increased weight dedicated to the structural weight fraction of the head. As a result, golf club designs using short fiber reinforced polymer material for the body will sacrifice some aspect of performance due to the head being forced to be either smaller, heavier, plainer in shape, have material distributed in less advantageous locations (e.g., central region of sole or crown) or have less discretionary material for adjusting CG position.

BRIEF SUMMARY OF THE INVENTION

The present invention seeks to enable the design and fabrication of a golf club head consisting of a conventional metallic face or face-cup and a non-metallic body or portion of the body. It is desired to make the non-metallic portion of the body from a material that has adequate durability, adequate stiffness and low density but that is significantly less expensive that laminated composite material and can be fabricated in high rates using processes such as injection molding.

The difficulty is that most non-metallic materials that are suitable for high rate production processes, such as injection molding, are not structurally suitable for this application. Conversely, non-metallic materials that are structurally suitable for this application are not suitable for high rate production processes, such as injection molding. The advantage to be gained from this invention is principally cost reduction and enhanced production flexibility (higher thru-put) compared to that available from laminated composite materials.

One solution, instead of trying to mold the whole body at once, is splitting the aft-body component into two (or more) pieces. By splitting the part, we are able to make two separate pieces which are relatively easy to mold. The parts are bonded together to form a complete composite aft-body. The aft-body is then finished and bonded to a finished face cup in the same way current multiple material driver golf club heads are assembled. The relevant range of thickness for driver heads is 0.020 inch to 0.080 inch, and the present invention is able to mold to thicknesses throughout this range, preferably using a carbon/vinyl ester material. Alternatively, epoxy-based molding compounds are utilized since these materials provide better strength and impact resistance than vinyl ester. The use of smaller diameter fiber bundles (3 k tows versus the more standard 12 k tows) assist with molding thin components for a golf club head.

Another concern with the thin compression molded parts is variation in strength. Preliminary testing shows that the variation in strength increases as specimen thickness decreases. Without sufficient thickness, the random nature of the fiber distribution in these kinds of materials can lead to weak spots in the finished golf club head component. The preferred method that these materials can approach strength consistency is if the final golf club head component is thick enough (or the fiber bundle layers are thin enough) to allow for fiber orientation “averaging” through the thickness. In addition to making molding easier, smaller fiber bundle diameters assist with strength consistency by allowing for a more uniform distribution of fiber orientations for a given part thickness.

While standard molding compounds have a lower strength, stiffness and impact toughness than continuous fiber laminates, there are several ways that improve the material properties of these standard molding compounds. One way of improving the material properties of standard molding compounds is to utilize longer fibers and higher fiber content. In a preferred method, fibers as long as 2 inches are utilized to improve the material properties of standard molding compounds. In addition or alternatively, adding micro-and nano-fillers (carbon nanotubes, nanoclays, etc.) to the matrix material increases the material properties of standard molding compounds. Another approach to improve the material properties of standard molding compounds is to use a combination of continuous fiber-reinforcement (prepreg) and molding compounds.

Molding compounds allow for a reduction in scrap when compared to laminated parts thereby providing savings.

Exact placement of the raw material in the molding tool is not required in therefore the raw material is used in a form that allows for just one piece per golf club head component, which has the effect of eliminating the labor intensive lay-up process.

The standard compression molding process preferably uses hard metal tooling on both sides of the golf club head component. During the molding process, the material is forced into the cavity between the two tool surfaces. As a result, the IML surface is a precise as the OML surface. This capability allows for blending of sharp IML corners to alleviate stress concentrations.

A two-piece compression molded body allows for a body-over face joint or a body-under face joint. The hard metal tooling on the IML allows for a precise bond surface geometry on either side of the golf club head component. Vinyl ester matrix molding compounds preferably cure in as little as one minute. Quick curing epoxy-based molding compounds have cure times as low as five minutes. Injection molding eliminates the need for any consumable bladder. Pressure is applied to both sides of the golf club head component with hard metal tool surfaces.

The present invention preferably comprises a driver aft-body, which is made up of two or more injection molded parts. The driver aft-body is bonded to a metallic face cup to form a golf club head. The injection molded parts have a thickness between 0.020 inch and 0.080 inch, except for areas which may be thicker to accommodate joint geometry. The joints may have features specifically built in to prevent misalignment during bonding and assembly (see illustrations below). Molding compounds of interest will be reinforced by fibers, including carbon, fiberglass, aramid or any combination of the three. The fibers in the molding compound will be between ¼″ and 2″ long.

In a preferred embodiment of the present invention the golf club head comprises a face component comprising a striking plate portion and a return portion extending rearward from the striking plate portion and an aft-body attached to the return portion, the aft-body comprising a crown portion and a sole portion joined together. The aft-body is composed of an injection molded compound comprising long fibers of at least 2.0 inches in length and the aft-body has a wall thickness ranging from 0.020 inch to 0.080 inch.

In another embodiment of the present invention, the golf club of the present invention comprises a face component comprising a striking plate portion and a return portion extending rearward from the striking plate portion and an aft-body attached to the return portion. The aft-body comprises a crown portion and a sole portion joined together. The aft-body is composed of a long fiber material comprising a thermoplastic material selected from the group consisting of nylon, polycarbonate, PPS, PEKK land PEEK, wherein the aft-body has a wall thickness ranging from 0.020 inch to 0.080 inch.

The present invention further comprises a method for forming an aft-body of golf club head. The method comprises combining a carbon fiber material in an amount of 20-70 volume % of the combination with a resin material in an amount of 30-80 volume % of the combination to form a pre-processing material. The method further comprises forming the pre-processing material into a long fiber precursor material and injecting the long fiber precursor material into a closed mold for a component of an aft-body of a golf club head. Lastly, the method comprises forming the component of the aft-body of a golf club head.

The fiber bundles used to create the molding compound are 1 k-12 k tows.

The matrix material for the molding compound is preferably a thermoset (epoxy, polyester, vinyl ester, etc.) or a thermoplastic (nylon, polycarbonate, PPS, PEKK, PEEK, etc.).

The fiber volume fraction of the molding compounds is preferably up to 70%.

The types of adhesives used to join the golf club head components together include, but are not limited to epoxies, acrylics, and films.

The injection molded body is preferably composed of more than one piece which is joined together after molding. The injection molded parts have wall thicknesses in the 0.020-0.080 inch range. The injection molded parts are joined together and bonded to a metallic face cup. The injection molded parts are preferably a combination of continuous reinforcement and molding compounds.

Having briefly described the present invention, the above and further objects, features and advantages thereof will be recognized by those skilled in the pertinent art from the following detailed description of the invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is an exploded view of a golf club head.

FIG. 2 is an isolated view of an alignment feature of a crown section of an aft-body of a golf club head.

FIG. 3 is an isolated view of a crown-sole joint of an aft-body of a golf club head.

FIG. 4 is an isolated view of a face component aft body joint of a golf club head.

FIG. 5 is a graph of a standard deviation n in flexural strength versus thickness.

DETAILED DESCRIPTION OF THE INVENTION

As shown in the figures, the club head has alignment features for proper assembly.

As shown in FIG. 5, the standard deviation in flexural strength decreases as the wall thickness increases.

The final golf club head is preferably as disclosed in U.S. Pat. No. 6,582,323 for a Multiple Material Golf Club Head, which is hereby incorporated by reference in its entirety.

Alternatively, the final golf club head is preferably as disclosed in U.S. Pat. No. 7,320,646 for a Multiple Material Golf Club Head, which is hereby incorporated by reference in its entirety.

Alternatively, the final golf club head is preferably as disclosed in U.S. Pat. No. 7,431,666 for a Golf Club Head With A High Moment of Inertia, which is hereby incorporated by reference in its entirety.

Alternatively, the final golf club head is preferably as disclosed in U.S. Pat. No. 7,390,269 for a Golf Club Head, which is hereby incorporated by reference in its entirety.

Variable face thickness patterns of the striking plate insert are disclosed in U.S. Pat. No. 6,471,603, for a Contoured Golf Club Face, U.S. Pat. No. 6,368,234 for a Golf Club Striking Plate Having Elliptical Regions of Thickness, U.S. Pat. No. 6,398,666 for a Golf Club Striking Plate With Variable Thickness, U.S. Pat. No. 7,448,960, for a Golf Club Head With Face Thickness which are all owned by Callaway Golf Company and which pertinent parts related to the face pattern are hereby incorporated by reference.

The mass of the club head of the present invention ranges from 165 grams to 250 grams, preferably ranges from 175 grams to 230 grams, and most preferably from 190 grams to 205 grams. Preferably, the subassembly preferably has a mass ranging from 140 grams to 200 grams, more preferably ranging from 150 grams to 180 grams, yet more preferably from 155 grams to 166 grams, and most preferably 161 grams. The crown component has a mass preferably ranging from 4 grams to 20 grams, more preferably from 5 grams to 15 grams, and most preferably 7 grams.

The golf club head preferably has that ranges from 290 cubic centimeters to 600 cubic centimeters, and more preferably ranges from 330 cubic centimeters to 510 cubic centimeters, even more preferably 350 cubic centimeters to 495 cubic centimeters, and most preferably 415 cubic centimeters or 470 cubic centimeters.

The center of gravity and the moment of inertia of a golf club head are preferably measured using a test frame (X^(T), Y^(T), Z^(T)), and then transformed to a head frame (X^(H), Y^(H), Z^(H)). The center of gravity of a golf club head may be obtained using a center of gravity table having two weight scales thereon, as disclosed in U.S. Pat. No. 6,607,452, entitled High Moment of Inertia Composite Golf Club, and hereby incorporated by reference in its entirety.

The moment of inertia, Izz, about the Z axis for the golf club head preferably ranges from 2800 g-cm² to 5000 g-cm², preferably from 3000 g-cm² to 4500 g-cm², and most preferably from 3750 g-cm² to 4250 g-cm². The moment of inertia, Iyy, about the Y axis for the golf club head preferably ranges from 1500 g-cm² to 4000 g-cm², preferably from 2000 g-cm² to 3500 g-cm², and most preferably from 2400 g-cm² to 2900 g-cm². The moment of inertia, Ixx, about the X axis for the golf club head 40 preferably ranges from 1500 g-cm² to 4000 g-cm², preferably from 2000 γ-cm² to 3500 g-cm², and most preferably from 2500 g-cm² to 3000 g-cm².

The golf club head preferably has a coefficient of restitution a (“COR”) ranging from 0.81 to 0.875, and more preferably from 0.82 to 0.84. The golf club head preferably has a characteristic time (“CT”) as measured under USGA conditions of 256 microseconds.

In a preferred embodiment of the present invention the golf club head comprises a face component comprising a striking plate portion and a return portion extending rearward from the striking plate portion and an aft-body attached to the return portion, the aft-body comprising a crown portion and a sole portion joined together. The aft-body is composed of an injection molded compound comprising long fibers of at least 2.0 inches in length and the aft-body has a wall thickness ranging from 0.020 inch to 0.080 inch. The injection molded compound preferably comprises a long fiber polyamide material. Alternatively, the injection molded compound comprises a long fiber polyphtalamide material. The injection molded compound may alternatively comprise a long fiber polyphenylene sulfide material. On the other hand, the injection molded compound may comprise a long fiber thermoplastic polyurethane material.

In another embodiment of the present invention, the golf club of the present invention comprises a face component comprising a striking plate portion and a return portion extending rearward from the striking plate portion and an aft-body attached to the return portion. The aft-body comprises a crown portion and a sole portion joined together. The aft-body is composed of a long fiber material comprising a thermoplastic material selected from the group consisting of nylon, polycarbonate, PPS, PEKK land PEEK, wherein the aft-body has a wall thickness ranging from 0.020 inch to 0.080 inch.

The present invention further comprises a method for forming an aft-body of golf club head. The method comprises combining a carbon fiber material in an amount of 20-70 volume % of the combination with a resin material in an amount of 30-80 volume % of the combination to form a pre-processing material. The method further comprises forming the pre-processing material into a long fiber precursor material and injecting the long fiber precursor material into a closed mold for a component of an aft-body of a golf club head. Lastly, the method comprises forming the component of the aft-body of a golf club head.

In one embodiment, the long fiber precursor material may have a carbon fiber of at least 0.43 inches in length. In another embodiment, the component of the aft-body has a wall thickness ranging from 0.020 inch to 0.080 inch. In yet another embodiment, the pre-processing material further comprises a filler material. In yet another embodiment, the filler comprises KEVLAR, fiberglass or a fibrous material. In an alternative embodiment, the carbon fiber material of the pre-processing material has a specific gravity ranging from 1.6 to 2.1 and a tensile modulus ranging from 25 to 50 Msi, and the resin material has a specific gravity ranging from 1.0 to 1.7. In yet another embodiment, the resin material is a thermoplastic material. The resin material may alternatively be a polyamide material and the carbon fiber material is present in an amount of approximately 40% of the volume of the combination. The resin material may alternatively be a polyphthalamide material and the carbon fiber material is present in an amount of approximately 40% of the volume of the combination.

In yet another embodiment, the resin material is a polyphenylene sulfide material and the carbon fiber material is present in an amount of approximately 50% of the volume of the combination.

Alternatively, the resin material is a thermoplastic polyurethane elastomer material and the carbon fiber material is present in an amount of approximately 50% of the volume of the combination. In yet another embodiment, the component of the aft-body is a crown portion. And in another preferred embodiment, the component of the aft-body is a sole portion.

The aft body is preferably constructed from a “long fiber” material consisting of the following combination of constituent materials: 20-70% carbon (graphite) fiber b volume; 30-80% thermoplastic or thermoset polymer resin by volume; Up to 20% of other filler materials, including other fibers (Kevlar, fiberglass or the like).

The constituent materials having the following properties: thermoplastic or thermoset polymer resin having a specific gravity between 1.0 and 1.7; carbon (graphite) fiber specific gravity between 1.6 and 2.1; carbon (graphite) fiber tensile modulus of between 25 and 50 Msi.

Prior to processing (entering into the injection molding hopper), into the club head body or specimen the constituent materials are combined (by a material supplier such as Ticona) into a “long fiber” precursor material with the following properties: Carbon fibers are nominally greater than 0.100 inch long.

After processing (plastication and injection into a closed mold), the material has the following properties as measured by testing molded coupons. Carbon fibers are generally dispersed throughout the material in a non-orderly manner. The tensile strength as measured by testing a standard dog-bone test specimen per ASTM-D-638 is greater than 20 Ksi. The tensile modulus as measured by testing a standard dog-bone test specimen per ASTM-D-638 is greater than 2 Msi. The toughness as measured by testing a standard notched IZOD specimen per ASTM-D-256 is greater than 2 ft-lb/inch. The specific gravity is between 1.2 and 2.0. After processing into a club head the nominal thickness of the body is not greater than 0.050″ and is preferably 0.040″ or less (maybe locally thicker).

The present invention preferably uses collimated “long fiber” thermoplastic precursor material such as that supplied by Ticona Corporation. Some examples of this type of material are as follows: PA66-CF40 (polyamide 66 with 40% long carbon fiber); PPA-CF40 (polyphthalamide with 40% long carbon fiber); PPS-CF50 (polyphenylene sulfide with 50% long carbon fiber); TPU-CF50 (thermoplastic polyurethane elastomer with 50% long carbon fiber).

The long fiber precursor, or pellet, is shown below. The pellet is approximately 0.43 inch long as shown, but may be adjusted to be any length greater than 0.10 inch.

The key discovery related to this material is that the combination of strength and toughness available from “long fiber” material is adequate for the club head body application. Whereas the strength and toughness available from short fiber reinforced polymer or unreinforced polymer is not adequate. The strength and toughness available from laminated composite is more than adequate, but at a higher cost and slower cycle time.

The conclusions are based on results of air cannon testing preformed to simulate accelerated exposure to golf ball strikes. The relative strengths and toughness based on air cannon testing is shown in Table One.

TABLE ONE AIR CANNON HITS TO FAILURE AT 110 MPH IN MATERIAL THE LOW CENTER Unreinforced polymer 1 PSU 1 PPA 40% carbon Short Fiber 5 PBT 30% carbon Short Fiber 1 PET 30% carbon Short Fiber 1 RTPU 20% carbon Short Fiber 1 PEI 10% carbon Short Fiber 1 PC/ABS 10% carbon Short Fiber 1 POM 10% glass Short Fiber 1 PP 30% glass Short Fiber 1 PA6 30% glass Short Fiber 1 PA66 40% carbon LONG FIBER 2714

From the foregoing it is believed that those skilled in the pertinent art will recognize the meritorious advancement of this invention and will readily understand that while the present invention has been described in association with a preferred embodiment thereof, and other embodiments illustrated in the accompanying drawings, numerous changes, modifications and substitutions of equivalents may be made therein without departing from the spirit and scope of this invention which is intended to be unlimited by the foregoing except as may appear in the following appended claims. Therefore, the embodiments of the invention in which an exclusive property or privilege is claimed are defined in the following appended claims. 

1. A golf club head comprising: a face component comprising a striking plate portion and a return portion extending rearward from the striking plate portion; an aft-body attached to the return portion, the aft-body comprising a crown portion and a sole portion joined together, the aft-body composed of an injection molded compound comprising long fibers of at least 2.0 inches in length, wherein the aft-body has a wall thickness ranging from 0.020 inch to 0.080 inch.
 2. The golf club head according to claim 1 wherein the injection molded compound comprises a long fiber polyamide material.
 3. The golf club head according to claim 1 wherein the injection molded compound comprises a long fiber polyphtalamide material.
 4. The golf club head according to claim 1 wherein the injection molded compound comprises a long fiber polyphenylene sulfide material.
 5. The golf club head according to claim 1 wherein the injection molded compound comprises a long fiber thermoplastic polyurethane material.
 6. A golf club head comprising: a face component comprising a striking plate portion and a return portion extending rearward from the striking plate portion; an aft-body attached to the return portion, the aft-body comprising a crown portion and a sole portion joined together, the aft-body composed of a long fiber material comprising a thermoplastic material selected from the group consisting of nylon, polycarbonate, PPS, PEKK land PEEK, wherein the aft-body has a wall thickness ranging from 0.020 inch to 0.080 inch.
 7. A method for forming an aft-body of golf club head, the method comprising: combining a carbon fiber material in an amount of 20-70 volume % of the combination with a resin material in an amount of 30-80 volume % of the combination to form a pre-processing material; forming the pre-processing material into a long fiber precursor material; injecting the long fiber precursor material into a closed mold for a component of an aft-body of a golf club head; and forming the component of the aft-body of a golf club head.
 8. The method according to claim 7 wherein the long fiber precursor material has a carbon fiber of at least 0.43 inches in length,
 9. The method according to claim 7 wherein the component of the aft-body has a wall thickness ranging from 0.020 inch to 0.080 inch.
 10. The method according to claim 7 wherein the pre-processing material further comprises a filler material.
 11. The method according to claim 10 wherein the filler comprises KEVLAR, fiberglass or a fibrous material.
 12. The method according to claim 7 wherein the carbon fiber material of the pre-processing material has a specific gravity ranging from 1.6 to 2.1 and a tensile modulus ranging from 25 to 50 Msi, and the resin material has a specific gravity ranging from 1.0 to 1.7.
 13. The method according to claim 7 wherein the resin material is a thermoplastic material.
 14. The method according to claim 7 wherein the resin material is a polyamide material and the carbon fiber material is present in an amount of approximately 40% of the volume of the combination.
 15. The method according to claim 7 wherein the resin material is a polyphthalamide material and the carbon fiber material is present in an amount of approximately 40% of the volume of the combination.
 16. The method according to claim 7 wherein the resin material is a polyphenylene sulfide material and the carbon fiber material is present in an amount of approximately 50% of the volume of the combination.
 17. The method according to claim 7 wherein the resin material is a thermoplastic polyurethane elastomer material and the carbon fiber material is present in an amount of approximately 50% of the volume of the combination.
 18. The method according to claim 7 wherein the component of the aft-body is a crown portion.
 19. The method according to claim 7 wherein the component of the aft-body is a sole portion. 